The present invention relates to a seat belt retractor.
WO 00/71394 teaches a seat belt retractor having a belt reel on which and from which the belt webbing of the seat belt can be wound and unwound. The belt reel is rotatably mounted in a frame having two frame legs. A torque rod extending along the axis of rotation of the belt reel is arranged in the belt reel. The torque rod is connected in the region of its one end to a first belt reel part arranged inside a frame leg aperture and in the region of its other end to a second belt reel part receiving the wound seat belt webbing. A blocking device supported on the frame can be brought into engagement with the first belt reel part. As a result in normal operating mode the belt reel is blocked against rotation in the direction of unwinding. The torque rod acts as a force limiter in the event of an excessive force effect issuing from the seat belt, for example in the event of forward displacement of the occupant wearing a seat belt during a crash. As a result the load exerted by the belt webbing on the body of the occupant wearing a seat belt is reduced. In the process the second belt reel part is rotated with respect to the first belt reel part blocked on the frame by torsion of the torque rod, so part of the seat belt webbing is unwound from the second belt reel part with consumption of energy.
It is known from DE 44 26 479 C2 to provide a full load stop between the first belt reel part and the second belt reel part, via which rotation of the second belt reel part with respect to the first belt reel part blocked on the frame is stopped after unwinding of a certain length of the wound seat belt webbing and the belt webbing is completely blocked.
While it is known from U.S. Pat. No. 5,779,177 to support the blocking teeth provided on the blocked belt reel on the inner edge of the frame leg aperture the known retractor does not have a torque rod as energy absorber. The region of the inner edge of the frame leg aperture on which the blocked teeth of the belt reel are supported in the radial direction is reduced locally in terms of its wall thickness in order to achieve a deformation in the support region.
The annular inwardly painting projections about the two frame leg apertures provided on both frame legs known from U.S. Pat. No. 4,453,681 serve to axially position the belt reel. The belt reel is blocked against rotation outside the frame leg aperture.
There is provided in accordance with the present invention a seat belt retractor comprising: a belt reel having two belt reel parts for receiving seat belt webbing wrapped around the belt reel; a frame having two frame legs in which frame the belt reel is rotatably mounted; a torque rod arranged in the belt reel, said torque rod having a first end and in the region of said end the torque rod is connected to the first belt reel part arranged inside an aperture in a frame leg, said torque rod having a second end and in the region of said second end the torque rod is connected to the second belt reel part; and a blocking device for engaging a belt reel part with support in the plane of at least one of the two frame legs, wherein in the event of an excessive force effect issuing from the seat belt the second belt reel part can be rotated with respect to the first belt reel part blocked on the frame by torsion of the torque rod, the inner edge of the aperture in the frame leg, in which the first belt reel part is arranged, is widened in the axial direction in the region of a plurality of peripheral segments with respect to the thickness of the frame leg in the axial direction by the formation of segmental faces arranged round the belt reel axis.
To this end the inner edge of the frame leg aperture in which the first belt reel part is arranged is widened in the axial direction in the region of a plurality of peripheral segments with respect to the thickness of the frame leg in the axial direction. Consequently segmental faces extending in the axial direction and arranged around the belt reel axis are formed.
Owing to the axial indentation of the inner edge of the frame leg aperture, at least in two peripheral segments, against which the blocked belt reel part rests in the radial direction in the event of excessive belt webbing extension force, the blocked first belt reel part is prevented from being displaced so far out of the frame leg aperture in the axial direction owing to the axial extension of the torque rod upon its torsion that it is no longer supported on the inner edge of the frame leg aperture. Owing to the corresponding indentation of the segmental faces at the inner edge of the frame leg aperture, the axial extension of the torque rod is taken into account so that reliable support for the first belt reel part in the radial direction is always ensured it is also ensured that the blocking device, preferably a pawl, is always engaged with the first belt reel part even when the torque rod comes into effect as en energy absorber. To this end this first belt reel part can in a known manner comprise engaging teeth on its circular peripheral edge.